Top of the Tongue - Angled Harmonica
Knowing that we use the top of the tongue for our tongue blocking, and we commonly cover four holes with our tongue (the pull articulation for example) and even at times five holes (5-hole octave pulls and pull-slaps), it makes sense to tilt the face if the harmonica (the hole side, what faces you) downward. This downward tilt (10 degrees to as much as 45 degrees) allows the harmonica to match the angle of your tongue, instead of raising the middle of your tongue and pushing it outward towards the harmonica. Experiment with your tongue blocking while using this tilt, you may like it.